The present invention relates to a liquid type development device for developing an electrostatic latent image, which is formed by electronic photography, electrostatic recording, ionography, etc., using a liquid developer; and, the invention especially relates to features for improving th e ease of maintenance and the convenience of use of a development device using liquid type development in the formation of images.
Since toner having fine particles whose diameters are less than 1 xcexcm can be used in a liquid type development device, a high-quality image, which is a faithful reproduction of its electrostatic latent image, can be obtained.
Liquid type development apparatuses using a liquid developer are disclosed, for example, in Japanese Patent Application Laid-Open Hei 11-15280 and Japanese Patent Application Laid-Open Hei 8-137285.
In the liquid type development device disclosed in Japanese Patent Application Laid-Open Hei 11-15280, a developer supply cartridge is filled with supplementary liquid developer along with high-pressure liquidized gas, and supplementary liquid developer is supplied to a developer-storing container for holding liquid developer by ejecting the supplementary liquid developer from the developer supply cartridge when the supply of liquid developer becomes necessary. This developer supply cartridge filled with supplementary liquid developer can be easily exchanged.
Further, the liquid type development device disclosed in Japanese Patent Application Laid-Open Hei 11-137285 includes a tube type container filled with a liquid developer having a high viscosity, in which a toner is intensively dispersed in an insulating liquid; a compressing device for extruding the liquid developer contained in the tube type container by squeezing out the liquid developer; and a development belt for holding and carrying the liquid developer extruded from the tube type container. Furthermore, the toner is fed to an electrostatic latent image on a photo conductor by bringing the development belt in contact with the photo conductor via the liquid developer. Moreover, since the liquid developer-storing means is implemented by use of a cartridge device, it is possible to supply or exchange the liquid developer without contaminating the user""s hands.
In addition, techniques to improve the ease of maintenance for a liquid type development device by detecting and storing an indication of the amount of liquid developer remaining in a cartridge, are disclosed in Japanese Patent Application Hei 8-224885 and Japanese Patent Application Hei 11-314375.
In the techniques disclosed in Japanese Patent Application Hei 8-224885 and Japanese Patent Application Hei 11-314375, an ID number is allocated to each ink cartridge, and the amount of ink remaining in the cartridge is detected and the value thereof is stored. Accordingly, managing the amount of remaining ink is possible for each ink cartridge. Thus, even if an ink cartridge is exchanged with another one in mid-course, it is possible to entirely use up the ink remaining in the exchanged cartridge by attaching the cartridge again.
However, the above conventional techniques have the following problems. That is, since the conventional liquid type development device has no means for recovering liquid developer remaining in the liquid developer-storing device, it is desirable to entirely use up the liquid developer in the liquid developer-storing device once liquid developer is fed to the liquid developer-storing device from a developer supply cartridge; however, this leads to the problem that much unused developer remains if only a few copies are developed. In this regard, since the liquid developer-storing device is not sealed, the liquid developer will dry out, and dried developer will be deposited on the developer-holding device, which in turn deteriorates the quality of a developed image.
Further, in conventional liquid type development devices, since liquid developer is directly fed to a developer-holding device from a developer-storing means, the developer-storing means must be precisely controlled, which in turn deteriorates the tractability of the liquid development apparatuses. Furthermore, maintenance of the development apparatuses is difficult if the developer-holding device is composed of multistage rollers, since liquid developer applied onto the developer-holding device becomes dried and tends to form deposits, which in turn deteriorates the quality of a developed image.
In addition, in the disclosed conventional techniques, since no technique for promoting the recycling of remaining liquid developer and its container has been indicated, there is a fear that an increase in waste products will have an adverse effect on the environment.
An object of the present invention is to provide a liquid type development device which is capable of solving the above-described problems. Another object of the present invention is to provide a maintenance method for a liquid type development device, and to a method of efficiently recovering unused and remaining supplementary liquid, which is added so as to keep the concentration of liquid developer in the liquid type development device constant.
To achieve the above objects, the present invention provides a liquid type development device for developing an electrostatic latent image formed on an image-holding device by using a liquid developer made of a highly insulating solvent and toner particles dispersed in the solvent, the development apparatus comprising a liquid developer tank detachably situated in a cartridge; and at least one supplementary liquid tank containing supplementary liquid to be added to the liquid developer contained in the liquid developer tank so as to keep the concentration of nonvolatile components, which comprise the toner particles, in the liquid developer. Further, the cartridge in the development apparatus includes a memory device for storing information of the amount of supplementary liquid remaining in the supplementary liquid tank.
As described above, by setting the liquid developer tank and the supplementary liquid tank in the same cartridge, the number of parts which should receive maintenance can be reduced, and this improves the ease of maintenance of the development apparatus. Further, by providing a means for storing information as to the amount of remaining supplementary liquid in the cartridge, since the cartridge is recycled by the unit of a cartridge when it is recycled, maintenance-managing of the development apparatus will become easy, which in turn can improve the efficiency of recycling the supplementary liquid.
Furthermore, by calculating a discount price of a newly bought cartridge, corresponding to the amount of the remaining supplementary liquid, a user""s tendency of casting away the remaining supplementary liquid can be suppressed, and a user""s willingness to recycle the remaining supplementary liquid can be improved, which in turn can improve the efficiency of recovering the remaining supplementary liquid.
Also, by increasing the discount rate in phases corresponding to an increase of the remaining supplementary liquid, the user""s tendency of casting away the remaining supplementary liquid can be suppressed.
Moreover, by changing the amount of supplementary liquid fed to the liquid developer, corresponding to the print ratio, since the concentration of nonvolatile components in the liquid developer can be approximately kept constant, the development can be stably continued.
Further, by preparing two kinds of supplementary liquid having different concentration levels of nonvolatile components, that is, concentration levels higher and lower than that of the liquid developer, since the concentration of nonvolatile components in the liquid developer can be approximately kept constant even if an image of any print ratio is developed, the development can be stably continued.
Furthermore, by providing an infiltration film at the boundary between the liquid developer and the supplementary liquid, since the concentration of the nonvolatile components in the liquid developer is kept constant by the action of the infiltration film, the concentration of the nonvolatile components in the liquid developer becomes more stable.
Moreover, in using a liquid type development device for developing an electrostatic latent image formed on an image-holding device by using liquid developer made of a highly insulating solvent and toner particles dispersed in the solvent, by giving a discount price privilege to a user who has turned in a used development device for recovery of the used development device, corresponding to the amount of supplementary liquid remaining in the development device, a user""s tendency of casting away the remaining supplementary liquid can be suppressed. In addition, a user""s willingness to recycle the remaining supplementary liquid can also be improved, and the efficiency of recovering supplementary liquid which remains yet can be improved.
On top of that, by using liquid of a developer including nonvolatile components of 1-30 wt % concentration, since the amount of liquid developer fed to the image-holding device can be reduced, it is possible to simplify the developer-feeding means. Also, since the amount of necessary liquid developer becomes small, the volume capacity of a liquid developer-storing means can be reduced, and this makes it possible to downsize the liquid type development device, which in turn makes it possible to decrease the size of the liquid type development device using the development device.